Tension control in twisting machines and the like



April 16, 1957 w. DEWHIRST 2,788,633

TENSION CONTROL IN TWISTING MACHINES AND THE LIKE Filed Jan. 13, 1956 7 Sheets-Sheet 1.

a. INVENTORZ WILLIAM DEWHIRST W. DEWHIRST ril 16, 1957 TENSION CONTROL IN TWISTING MACHINES AND THE LIKE Filed Jan. 13, 1956 7 Sheets-Sheet. 2

April 16, 1957 w. DEWHIRST 2,788,632

TENSION 'CbNTROL IN TWISTING MACHINES AND THE LIKE Filed Jan. 13, 1956 7 Shets-Sheet 3 INVENTORI WILLIAM DEWHIRST BY W4 ATTYS.

Ap 5 w. DEWHIRST 2,788,632

TENSION CONTROL IN TWISTING MACHINES AND THE LIKE Filed Jan. 13, 1956 7 Sheets-She e't 4 WILLIAM DEWHIRST BY W4 lNVE-NTOR'.

April 16, 1957 w, sT 2,788,632

TENSION CONTROL IN TWISTING MACHINES AND THE LIKE Filed Jan. 13, 1956 7 Sheets-Sheet 5 FIG.6.

I mvcmon: WILLIAM DEWHIRST r J BY l ATTXS.

W. DEWHIRST April 16, 1957 TENSION CONTROL IN TWISTING MACHINES AND THE LIKE Filed Jan. 15, 1956 7 Sheets-Sheet 6 INVENTOIR'. WILLIAM DEW HIRST AT TYS.

,TENSION CONTROL IN- TWISTING MACHINES AND THE LIKE Filed Jan. 13. 1956 W. DEWHIRST April 16, 1957 7 Sheets-Sheet 7 INVE NTOR WILLIAM DE WHIRS T BY 'W ATTYS.

United States atent' O TENSION CONTROL IN TWISTING MACHINES AND THE LIKE William Dewhirst, Philadelphia, Pa., assignor to Haskell- Dawes Machine Company, Inc., Philadelphia, Pa, a corporation of Pennsylvania Application January 13, 1956, Serial No. 558,989

16 Claims. (Cl. 57-68) This invention relates to control of tension of the strand material in twising machines and the like wherein the strand material is delivered at a constant rate to a driven take-up or winding reel and is wound thereon by means of a driven flyer or like member. Thus, in one type of twisting machine, the capstans (driven at constant speed by the flyer) receive the strand material after it has passed through a sizing die or tube, and the capstans deliver the material at a constant rate to a driven winding reel upon which the strand material is wound by the flyer and associated reciprocating feed means. The present invention is directed particularly to the control of tension of the strand material in such a machine.

In machines of this general character, it is highly desirable that the tension of the strand material be maintained essentially constant of an optimum tension, i. e., within a narrow predetermined range of tensions under widely varying conditions of operation. This is particularly important in the case of twisting machines. Such machines are required to twist various strand materials, such as wire, textile yarn, asbestos, paper, etc. and are required to furnish a precise uniform twist in each reeled quantity of the twisted strand material. While some tension of the strand material is essential to the proper Winding or reeling of the material, excess tension or lack of tension may cause breakage or at least may cause variation of the twist and/ or the diameter of twisted material and thereby result in spoilage.

In machines of the character above mentioned, it has been found expedient to control the tension of the strand material by varying the speed of the winding reel through the medium of a controllable friction clutch interposed in the drive for the winding reel. It is necessary that the winding reel be driven at a rotational speed greater than the rotational speed of the flyer, in order that the winding operation may be performed, and to insure proper control of the tension of the strand material, the speed relationship between the Winding reel and the flyer must be accurately controlled. In practice, the fiyer is driven at constant speed, and the speed of the winding reel is controlled through the medium of the above-mentioned friction clutch. Various prior arrangements have been proposed for maintaining the tension of the strand material within permissible limits, but none of such arrangements has been adequate to insure satisfactory control during starting, running and stopping of the machine. Inertia and momentum of the winding reel. and of the flyer tend to vary their speed relation during starting and stopping. Moreover, the mass of the wound material, which increases as the winding operation proceeds, also tends to vary the speed relationship between the reel and the flyer. Consequently, the provision of a satisfactory arrangement for maintaining the tension of the strand material essentially constant at all times has presented a serious problem.

The principal object of the present invention is to provide a tension control arrangement which overcomes the difliculties and which solves the problems of accurate control. I

By this invention, there is provided, in amachine of the character above mentioned, a feed back control arrangernent which responds to variations in the rate of winding take-up onto the reel and which controls the torque applied to the winding reel so as to maintain the tension of the strand material essentially constant at all times.

The invention may be fully understood. from the following detailed description with reference to the accompanying drawings, in which:

Fig. l is a front elevational view of a twisting machine of the above-mentioned type embodying the present invention;

Fig. 2 is a fragmentary elevational view showing the passage of the strand material through the sizing die or tube;

Fig. 3 is a sectional view of the left-hand portion of the machine, taken along the longitudinal axis thereof;

Fig. 4 is a similar view of the right-hand portion of the machine;

Fig. 5 is a sectional view taken along line 5--5 of Fig. 1;

Fig. 6 is a sectional view taken along line 6-6 of Fig. 1;

Fig. 7 is a sectional view taken along line 7-7 of Fig. 1;

Fig. 8 is a fragmentary sectional View taken along line 3-8 of Fig. 7;

Fig. 9 is an enlarged fragmentary sectional view taken along line 9--9 of Fig. 1; i

Fig. 10 is a sectional view taken along line 10-40 of Fig. 9;

Fig. 11 is a fragmentary sectional view taken along line 1l1l of Fig. 5;

Fig. 12 is a fragmentary perspective view of the reciprocating mechanism by which the strand material is wound on the winding reel;

Fig. 13 is a view taken along line 1313 of Fig. 3;

Fig. 14 is a fragmentary view taken along line 14- 14 of Fig. 15;

Fig. 15 is 'a perspective view of the capstans and the associated tension compensating mechanism; and

Fig. 16 is a diagrammatic illustration of the electrical circuit of the machine.

To a large extent, the machine illustrated is of conventional form, and for the present purpose a general description of the known structure will suflice.

Referring particularly to Figs. 1 to 4, a supporting framework 20 is provided having vertical standards 21 and 22 which provide the main means of support of the component parts of the machine. The winding reel 23 is carried by horizontally-aligned shafts 24 and 25, and the reel is driven through shaft 25 by means of a drive including a controllable friction clutch 26. This clutch is of conventional form, and it comprises coils 27, a friction ring 28, and a spring-biased friction plate 29 which is movable upon energization of the coils into engagement with the ring 28. Variation of the voltage applied to the coils 27 effects variation of the frictional engagement between the friction elements, and thus effects variation of the driving torque applied tothe shaft 25. The coils 27 are energized through collector rings 30 and associated brushes 31. Ring 28 is connected through the mechanical structure of the clutch to a collar 32 which is keyed to the shaft 25. Plate 29 is connected to a pulley 33 which is driven by belts 34 from one section of a dual pulley 35, which is driven by a constant speed motor 36 through electromagnetic clutch 41 (see Fig. 8).

Associated with the winding reel 23 is: the rotatable flyer 37 which isdriven through sleeve extension 38 and greases 3 pulley 39 keyed to said sleeve extension. The pulley 39 is driven by belts 40 from the smaller section of pulley 35. Thus the fiyer 37 is driven at constant speed through the belt and clutch connection to the constant speed driving motor.

Referring particularly to Fig. 3, the capstans 4-2 and 2-3 are rotatably mounted on bolts or studs 44 and 45 con nected to one side of the flyer 37. The capstans are rotatably driven through gear teeth provided thereon by a common central gear l6 on one end of a hollow shaft 47. The latter is rotatably driven by the flyer 37 through an outer sleeve 48 and the gear train (see Fig. 13) desig nated generally by reference numeral 49 which comprises gears 49a to 49g. Sleeve 48 has an end flange 56 through which it is connected to the flyer 37 by the bolts 44 and 45. Thus the capstans 42 and 43 are rotatably driven on the supporting bolts 44 and 45 at constant speed from the flyer 37.

The strand material 51 passes through a sizing die or tube 52 and through the hollow shaft 47 to a pulley 53 mounted on the flyer 37. From this pulley, the strand material passes around the capstans l2 and 4.3 which feed the strand material at a constant rate to the winding reel. In the illustration, the strand material 51 is shown as comprising a number of strands which are twisted as the pulley 53 rotates with the flyer. It is desired that the machine shall furnish uniform twist of the strand material and as previously pointed out, it is necessary to control the tension of the strand material not only to prevent possible breakage but also to prevent variation of the twist.

Disregarding for the time being the arrangement provided by this invention to control the tension of the strand material, said material is supplied to the winding reel via pulley 54 and the tubular section 55 of the flyer 37. As shown in Figs. 1, 6 and 12, the strand material 51 leaves the hollow section 55 via pulley 56. The two longitudinal sections 55 and 57 of the flyer 37 have slidable brackets 53 and 59 mounted thereon, and bracket 58 carries the pulley 56. These brackets are attached to a ring 64) which is rotatable within a channeled outer ring 61. The latter is carried by a supporting frame 62 having sleeve portions 63 and 64 which are slidable on stationary rods 65 and 66. During the winding operation, slow reciproeating motion is imparted to the supporting frame 62 and consequently to ring 61 by means of a driven reversing worm shaft 67 which operatively engages a hollow follower 68 forming part of frame 62. It will be understood that the reciprocating motion of the feed pulley 56 causes winding of the strand material back and forth on the winding reel 23.

As shown in Figs. 1 and 7, the worm shaft 67 is driven at relatively low speed through belts 69 and 76. Belt 6? extends from the motor driven pulley 35 to a pulley 71, while belt 70 extends from pulley 71 to pulley 72 mounted on (worm reduction drive) the worm shaft 6'7. Thus a substantial speed reduction is eifected between the motor shaft and the worm shaft 67.

From the foregoing description, it will be seen that the winding reel 23, the flyer 37, and the slowly reciprocating feed pulley 56 are all driven from the common driving motor 36, and as previously mentioned, the speed of the winding reel is controlled through the medium of the controllable friction clutch 26. In view of the fact that a fully wound reel may have substantial mass and therefore substantial momentum, it is desirable. to counteract the momentum of the wound reel during stopping by means of an electromatic brake. Thus, in the machine illustrated an electromagnetic brake 73 (Fig. 4) is provided, which may be generally similar in structure to the clutch 26, having a spring-biased friction plate 74 connected to sleeve 32, a friction ring 75 connected to a stationary member 76, and coils 77 which are energized to eifect operation of the brake.

As may be seen in Fig. 16, the clutch 26. and the driving motor 36 are energized by closing switch 130, but the brake 73 and starting clutch are under control of a start and stop relay 7%; controlled by start and stop switches 79 and 86. The relay '78 may be energized from supply conductors 81 through a transformer 82 by momentary closure of the start switch 79, the relay locking itself in through contacts 83. Contacts 35 control the brake 73 and the brake is energized when the relay is deenergized by opening of the stop switch 8% which is in the holding circuit of the relay. Contacts 86 control the circuit for energization of the clutch 41.

As thus far described, the machine is generally of known form, and the problem in the past has been to provide a suitable arrangement for maintaining essentially constant the tension of the strand material. In accord ance with the present invention, this is accomplished by means of the arrangement now to be described which includes a compensating potentiometer 37 (Fig. 16) for applying a variable voltage to the clutch 26. This potentiometer is operated automatically to control the speed of the winding reel so as to maintain the tension of the strand material within the desired range. Preferably the range of compensation by the potentiometer $7 is preset according to the particular strand material by means of manually adjustable potentiometers 83 and lift it will be seen from Fig. 16 that the adjustment of potentiometer 131 is for Zero or null connection of potentiometer 88 and potentiometer 38 determines the maximum voltage which can be applied to the clutch 26 by the compensating potentiometer 87. The proper setting of potentiometer 38 Will prevent excessive hunting of the pulley 93 which will be described hereafter.

Referring now to Figs. 1, 3, 5 and 15, it will be recalled that the capstans 42 and 43 are rotatably driven from the flyer'37 through sleeve 4?, gear train 45 hollow shaft 47, and the common driving gear 46 which engages gear teeth on the capstans. Since the tlyer 37 is driven at a constant speed, the capstans 52. and 43 are likewise rotatably driven at a constantspeed.

In the preferred arrangement according to this invention, a ring gear 89 is provided which engages the gear teeth on the capstans 42 and 43 and this ring gear is frictionally coupled through a friction ring 949 to a plate or ring 91 which carries circularly arranged idler pulleys 92 and which also carries an idler pulley 93 mounted on an extension 94. As shown in Figs. 5 and ll, the frictional coupling between ring gear 239 and ring 91 through the friction ring is adjustable by means of spring arms 95 which are bolted to flange 5ft and which exert pressure on one side 'of the ring gear 39 whose opposite side engages the friction ring 2 d. As shown in Pig. ll, each of the spring arms 55 is engaged by a helical spring Q6 whose spring action is adjustable by means of adjusting screw 97 which is encircled by the spring 96 and which extends through an aperture in the associated arm $5 into threaded engagement with the flange 51 Since the adjusted friction corresponds to certain tension or pull on mornber 91 causing a relative movement between it and member 4-8, this pull may be simulated by a spring scale when adjusting screws 97.

The frictional coupling means may be replaced by direct spring coupling means without major modifications of the machine. The relative slippage characteristics between member 413 and ring 91 using a spring as the coupling will result in a certain amount of non-linearity of response causing same error variation in the desired constant strand tension. Moreover, adjustment is usually not possible with spring coupling, but the difficulties normally experienced in adjusting the frictional coupling members is eliminated so that for many applications spring coupling will be preferred.

As best seen in Figs. 5 and 15, the strand material 51.

passes from the capstans 42 and 43 about .a puller-v96 carried by the flyer .37, and then passesin a loop in en gagement with some of the pulleys 92 about the pulley 93. The strand material then passes about pulley 54 into the hollow section 55 of the fiyer as previously described. As hereinafter described, the length of the loop between pulley 98 and pulley 54 is automatically varied in response to variation of the speed relationship between the constant speed flyer 37 and the winding reel 23, and the speed of the latter is controlled so as to maintain the tension of the strand material essentially constant. Ring 91, on which pulley 93 is mounted, is rotatably mounted on flange 50 (see Fig. 3). Relative movement between ring 91 and sleeve 48 effects adjustment of the potentiometer 87 to vary the voltage applied to clutch 26 so as to vary the speed of the winding reel 23.

Referring particularly to Figs. 1, 3, 9 and 10, a chain sprocket 99 is mounted on ring 91 and is retained therewith by retaining plate or ring 100 held by the bolts 44 and 45. Sprocket 99 is connected through chain 101 to a sprocket 102 mounted on the end of a rotatable shaft 103 (see Fig. 9) which extends within a housing 104 supported by the main framework 20. A gear 105 at the opposite end of shaft 103 meshes with a gear 106 which is free to turn on shaft 187. Gear 106 meshes with an idler gear 108 carried by a rocker member 109 secured to shaft 107 by set screw 110. Gear 108 meshes with a gear 111 on one end of a short shaft 112 rotatably supported by the rocker member 109. A gear 113, secured to the other end of shaft 112, meshes with a gear 114 which is free to rotate on shaft 107. A gear 115, secured to the outer end of shaft 107, meshes with a gear 116 secured to the end of rotatable shaft 117 of the potentiometer 87. The latter is supported by bracket 118 mounted on the casing 104.

As best shown in Fig. 3, a chain sprocket 119 is secured to sleeve 48, and a chain 120 connects this sprocket to a sprocket 121 mounted on one end of a shaft 122 (see Fig. 9) which extends within the casing 104. A gear 123, secured to the other end of shaft 122, meshes with a gear 124 secured to the end of a shaft 125 rotatably supported within the casing 104. Gear 124 meshes with gear 114 which, as previously noted, is freely rotatable on shaft 107.

The above-described arrangement constitutes a difierential drive by which the potentiometer shaft 117 is actuated in response to relative movement between sleeve 48 and ring 91. In operation of the machine, both of these elements rotate, and if they were to rotate at the same speed, there would be no actuation of shaft 107 and therefore no actuation of the potentiometer shaft 117. Under such condition, the rocker 109 would rer main stationary. When the ring 91 moves forwardly in relation to sleeve 48, the rocker member 109 is caused to move to effect turning of shaft 107, and the latter turns the potentiometer shaft 117 in a direction to increase the applied voltage to the clutch 26 so as to increase the speed of the winding reel 23. When ring 91 moves rearwardly in relation to sleeve 48, the rocker member 109 is moved in the opposite direction to effect turning of the potentiometer shaft 117 in a direction to reduce the voltage applied to clutch 26 so as to decrease the speed of the winding reel 23.

Prior to the operation of the machine for the twisting and winding of a particular strand material, the frictional coupling between ring 91 and the ring gear 89 is adjusted to correspond to a certain tension of the particular strand material not in excess of 25% of the breaking strength of the finished twisted material. This adjustment is made by means of the adjusting screws 97 of the compensat ing mechanism and the friction is thus adjusted to provide sufficient tension to hold the twisted strand from ballooning due to centrifugal force. The required ten sion can be calculated from various known factors such as the weight per foot of material, the speed of the fiyer and the distance from the center of rotation.

. The potentiometer 88 (see Fig. 16) is adjusted to en- 6 able at relatively wide range of compensation by the poten tiorneter 87.

The brake torque is adjusted by a potentiometer (not shown) to a value somewhat lower than the maximum torque applicable to the winding reel when potentiometer 87 is in its maximum voltage position. The potentiometer setting is determined for any selected value of brake torque by which physical readings using a spring scale. If the brake torque is too low in value, a full reel of wound material will run so far ahead of the flyer during stopping of the machine as to cause breakage of the material. On the other hand, if the brake torque is too high, the reel will stop too quickly and the momentum of the fiyer will cause it to run ahead and cause the material to balloon out of the flyer.

After the above-mentioned adjustments have been made, motor 36 is started by closing switch 130. Thereafter, the twisting and reeling operations of the machine are started by closing the starting switch 79. Starting switch 79 causes relay 78 to be energized, in turn causing clutch 41 to operate. During starting operation, the winding reel and the flyer accelerate until the machine reaches normal operating speed under the control of clutch 41. If the fiyer tends to gain momentum faster than the winding reel, the compensating mechanism will be driven in a direction to increase the torque on the winding reel, thus insuring that the reel will stay in ad- Vance of the flyer. That is to say, the ring 91 will be driven through the friction coupling ring slightly faster than the speed of sleeve 48, due to the decrease in the rate of Winding of the strand material, and the potentiometer 87 will be actuated in a direction to increase the voltage applied to clutch 26. On the other hand, if the torque driving the winding reel accelerates the reel faster than the flyer, the faster winding will cause take-up at a rate faster than the twisted strand material is being delivered by the capstans and hence the loop will be shortened despite opposition by the present tensions to cause backward movement of ring 91 in relation to sleeve 48 and hence to cause actuation of the potentiometer 87 in a direction to decrease the voltage applied to clutch 26 and thus decrease the torque applied to the winding reel. 9 a

When the machine reaches normal operating speed, the compensating mechanism automatically adjusts itself to maintain the proper speed differential between the winding reel and the flyer. If the speed of the Winding reel increases, the rate of delivery of the strand material increases shortening the loop and pulling arm 94 backwards and the ring 91 is caused to move backwardly in relation to sleeve 48, causing adjustment of potentiometer 87 in a direction to decrease the speed of the winding reel and thus restore the normal speed differential between it and the flyer. If the speed of the winding reel decreases, ring 91 is driven through the friction ring 90 forwardly in relation to sleeve 48, causing adjustment of potentiometer 87 in a direction to increase the speed of the winding reel and thus restore the normal speed diiferentiai between it and the fiyer. The ring 91 is free to adjust itself as required and may even hunt, if necessary, although in practice machines do not tend to hunt if properly adjusted. As the reel fills up the pulley 93 gradually advances to successively higher torque positions.

When the winding reel is full, the machine is stopped by means of the stop switch 30. The deenergization of relay 78 causes deenergization of clutch 41 and energization of brake 73. Thus, the winding reel and the flyer are mechanically disconnected from the shaft of the driving motor, and simultaneously the brake is applied to overcome the inertia of the winding reel. During stopping of the machine, thewinding reel tends to decelerate faster than the fiyer, the compensating loop lengthens causing increased torque to be applied through clutch 26,

'7' 7 thus maintaining the desired speed differential between the reel and the flyer during the stopping operation.

From the foregoing description, it will be seen that the invention provides an arrangement which detects variation of the speed differential between the Winding reel and the fiyer, and which acts to restore the normal speed differential so as to maintain the tension of the strand material essentially constant. It will also be seen that the detection of variation of the speed differential is effected by sensing variation of the tension of the material from the value corresponding to the friction setting of the compensating mechanism. In operation, the compensating mechanism effectively stores some of the strand material in the loop, and the material is drawn from the loop by the winding reel according to the length of the loop atany particular time.

While a preferred embodiment of the invention has been illustrated and described, the invention is not limited thereto but contemplates such modifications and further embodiments as may occur to those skilled in the art.

I. claim:

1. In a machine of the character described, a rota'ble winding reel, drive means for rotating said reel, electrically-operable means for varying the speed of said reel, means rotatable about said reel, means for driving said rotatable means at constant speed normally lower than the speed of said reel, means for supplying strand material at a constant rate to said reel through said rotatable means, adjustable means operable directly by the slack or pull of the strand material for applying a variable voltage to said electrically-operable means, and means responsive to variations in the rate of winding take up of the strand material onto the reel for adjusting said voltage-applying means to vary the speed of said reel in relation to the speed of said rotatable means so as to maintain the tension of the strand material essentially constant.

2. in a machine of the character described, a rotatable winding reel, drive means for rotating said reel, electrically-operable means for varying the speed of said reel, means rotatable about said reel, means for driving said rotatable means at constant speed normally lower than the speed of said reel, means for supplying strand material at a constant rate to said reel through said rotatable means, adjustable means for applying a variable voltage to said electrically operable means, means sensing slack or pull in the strand material due to changes in the rate of Winding take up onto the reel and engaged by the strand material as it passes from said supplying means to said rotatable means, and means operable by said sensing means upon variation of tension of the strand material for adjusting said voltage-applying means to vary the speed of said reel in relation to the speed of said rotatable means so as to maintain the tension of the strand material essentially constant.

3. In a machine of the character described, a rotatable winding reel, drive means for rotating said reel, electri- (rally-operable means for varying the speed of said reel, means rotatable about said reel, means for driving said rotatable means at constant speed normally lower than the speed of said reel, means for supplying strand material at a constant rate to said reel through said rotatable means, adjustable means for applying a variable voltage to said electrically-operable means, means sensing slack or pull in the strand material due to changes in the rate of winding take up onto the reel and engaged by the strand material as it passes from said supplying means to said rotatable means, frictional coupling means between said supplying means and said sensing means, and means operable by relative movement between said sensing means and said rotatable means for adjusting said voltage-applying means to vary the speed of said reel in relation to the speed of said rotatable means so as to maintain the tension of the strand material essentially constant.

4. In a machine of the character described, a rotatable arcades winding reel, drive means for rotating said reel, electrically-operable means for varying the 'speed of said reel, means rotatable about said reel, means for driving said rotatable means at constant speed normally lower than the speed of said reel, means for supplying strand material at a constant rate to said reel through said rotatable means, adjustable means for applying a variable voltage to said clectriclly-operable means, means sensing slack or pull in the strand material due to changes in the rate winding take up onto the reel and engaged by the s rand material as it passes from said supplying means to said rotatable .ieans, spring coupling means between said supplying means and said sensing means, and means operable by relative movement between said sensing means and said rotatable means for adjusting said voltage-applying means to vary the speed of said reel in relation to the speed of said rotatable means so as to maintain the tension of the strand material essentially constant.

5. in a machine of the character described, a rotatable xinding reel, drive means for rotating saidv reel, electrically-operable means for varying the speed of said reel, means rotatable about said reel, means for driving said rotatable means at constant speed normally lower than the specs of said reel, means for supplying strand material at a constant rate to said reel through said rotatable means, adjustable means for applying a variable voltage to said electrically-operable means, a pulley engaged by a loop of the strand material as it passes from said supplying means to said rotatable means, frictional coupling means be tween said supplying means and said pulley, and means operable by relative movement between said pulley and said rotatable means for adjusting said voltage-applying means to vary the speed of said reel in relation to the speed of said rotatable means so as to maintain the tension of the strand material essentially constant.

6. A. machine according to claim 5, further including means to enable adjustment of said frictional coupling means.

7. in a machine of the character described, a rotatable Winding reel, drive means for rotating said reel, electrically-operable means for varying the speed of said reel, a ilyer rotatable about said reel, means for driving said fiyerat constant speed normally lower than the speed of said reel, means for supplying strand material at a constant rate to said reel through said fiyer, adjustable means operable directly by the slack or pull of the strand mate rial for applying a variable voltage to said electricallyoperable means, and means responsive to variations in the rate of winding take up of the strand material onto the reel for adiusting said voltageapplying means to vary the speed of said reel in relation to the speed of said ilyer so as to maintain the tension of the strand material essentially constant.

8. In. a machine of the character described, a rotatable winding reel, drive means for rotating said reel, electrically-operable means for varying the speed of said reel, a ilyer rotatable about said reel, means for driving said iiyer at constant speed normally lower than the speed of said reel, means driven by said ilyer for supplying strand material at a constant rate to said reel through said flyer, adjustable means for applying variable voltage to said electricallyoperable means, means sensing slack or pull in the strand material due to changes in the rate of winding take up onto the reel and engaged by the strand material as it passes from said supplying means to said fiyer, frictional coupling means between said supplying means and said sensing means, and means operable by relative movement between said se. sing means and said ilyer for adjusting said voltage-applying means to vary the speed of said reel in relation to the speed of said fiyer so as to maintain the tension of the strand material essentially constant.

9. In a machine of the character described, a rotatable winding reel, drive means for rotating said reel, electrical lypperable means for varying the speed of said tool, a

fiyer rotatable about said reel, means for driving said fiyer normally lower than the speed of said reel, means driven by said fiyer for supplying strand material at a constant rate to said reel through said fiyer, adjustable means for applying a variable voltage to said electricallyoperable means, a pulley engaged by a loop of the strand material as it passes from said supplying means to said fiyer, frictional coupling means between said supplying means and said pulley, and means operable by relative movement between said pulley and said fiyer for adjust ing said voltage-applying means to vary the speed of said reel in relation to the speed of said fiyer so as to maintain the tension of the strand material essentially constant.

10. A machine according to claim 9, further including means to enable adjustment of said frictional coupling means.

11. In a machine of the character described, a rotatable winding reel, drive means for said reel including an elec trically-operable friction clutch through which the speed of said reel may be controlled, a fiyer rotatable about said reel, means for driving said fiyer at constant speed normally lower than the speed of said reel, capstans driven by said fiyer and serving to supply strand material at a constant rate to said reel through said fiyer, a potentiometer for applying a variable voltage to said clutch, means for detecting variation of the rate of winding take up onto said reel, and means operable by said detecting means for adjusting said potentiometer so as to restore the normal rate of take up by adjustment of the speed difierential between said reel and said fiyer and to maintain the tension of the strand material essentially constant.

12. In a machine of the character described, a rotatable winding reel, drive means for said reel including an electrically-operable friction clutch through which the speed of said reel may be controlled, a fiyer rotatable about said reel, means for driving said fiyer at constant speed normally lower than the speed of said reel, capstans driven by said fiyer and serving to supply strand material at a constant rate to said reel through said fiyer, a potentiometer for applying a variable voltage to said clutch, a pulley engaged by a loop of the strand material as it passes from said capstans to said fiyer, frictional coupling means between said captsans and said pulley, the pulley being movable relative to the fiyer upon variation of the rate of winding take up onto said reel, and means operable upon such movement of the pulley for adjusting said potentiometer so as to restore the normal rate of take up by adjustment of the speed differential between said reel and said fiyer and to maintain the tension of the strand material essentially constant.

13. A machine according to claim 12, further including means to enable adjustment of said frictional coupling means.

14. In a machine of the character described, a rotatable winding reel, drive means for said reel including an electrically-operable friction clutch through which the speed of said reel may be controlled, a fiyer rotatable about said reel, means for driving said fiyer at constant speed normally lower than the speed of said reel, capstans driven by said flyer and serving to supply strand material at a constant rate to said reel through said fiyer, a ring gear driven by said capstans, a rotatable member carrying pulleys over which the strand material passes in a loop between the capstans and said fiyer, frictional coupling means between said ring gear and said rotatable member, said member being movable relative to the flyer upon variation of the rate of winding take-up onto said reel, a potentiometer for applying a variable voltage to said clutch, and means operable by relative movement between said member and said fiyer for adjusting said potentiometer so as to restore the normal rate of take-up by adjustment of the speed differential between said reel and said fiyer and to maintain the tension of the strand material essentially constant.

15. In a strand twisting machine, a rotatable winding reel, drive means for said reel including an electricallyoperable friction clutch through which the speed of said reel may be controlled, a fiyer rotatable about said reel, means for driving said fiyer at constant speed normally lower than the speed of said reel, a pair of studs projecting from one side of said fiyer, a pair of capstans rotatably supported on said studs, means operable by rotation of said fiyer to rotate said capstans at constant speed, said capstans serving to supply strand material at a constant rate to said reel through said fiyer, a pulley engaged by a loop of the strand material as it passes from said capstans to said fiyer, frictional coupling means. between said capstans and said pulley, the pulley being movable relative to the flyer upon variation of the rate of winding take-up onto said reel, a potentiometer for applying a variable voltage to said clutch, and means operable upon movement of said pulley relative to the fiyer for adjusting said potentiometer so as to restore the normal rate of takeup by adjustment of the speed differential between said reel and said fiyer and to maintain the tension of the strand material essentially constant within predetermined limits.

16. In a strand twisting machine, a rotatable winding reel, drive means for said reel including an electricallyoperable friction clutch through which the speed of said reel may be controlled, a fiyer rotatable about said reel, means for driving said flyer at constant speed normally lower than the speed of said reel, a pair of studs projecting from one side of said fiyer, a pair of capstans rotatably supported on said studs, means operable by rotation of said fiyer to rotate said capstans at constant speed, said capstans serving to supply strand material at a constant rate to said reel through said fiyer, a ring gear driven by said capstans, a rotatable member carrying pulleys over which the strand material passes in a loop between the capstans and the fiyer, frictional coupling means between said ring gear and said rotatable member, said member being movable relative to the fiyer upon variation of the rate of winding take-up onto said reel, a potentiometer for applying a variable voltage to said clutch, and means operable by relative movement between said member and said fiyer for adjusting said potentiometer so as to restore the normal rate of take-up by adjustment of the speed differential between said reel and said flyer and to maintain the tension of the strand material essentially constant within predetermined limits.

References Cited in the file of this patent UNITED STATES PATENTS 1,900,309 Somerville Mar. 7, 1933 1,981,083 Somerville Nov. 20, 1934 2,338,848 Henning Jan. 11, 1944 2,484,179 MacCreadie Oct. 11, 1949 

